More spectrum - licensed, unlicensed and ASA.

Spectrum is the life-blood of wireless networks. In the quest to solve the 1000x mobile data challenge, spectrum is an important building block. We have introduced many innovations to better utilize existing spectrum and access new spectrum.

In the quest to solve the 1000x mobile data challenge, spectrum is an important building block. Given that spectrum is a finite resource, the industry is hard at work to utilize the available spectrum in the best possible manner and to identify opportunities to access more spectrum. There are primarily three approaches to make new spectrum available:

Traditional licensing for exclusive 3G/4G use, through auctions of cleared spectrum, remains the main option.

A new and innovative regime called ASA (Authorized Shared Access) that we are proposing with our partners. ASA is beneficial for the cases when spectrum can’t be cleared in a timely manner or at all locations.

Higher bands is one of the options for new spectrum, and 3.5 GHz band is a prudent initial candidate. Because of its smaller coverage, this band is also emerging as a global choice for small cells. Parts of this band may be licensed through traditional means, and other parts through ASA.

Maximizing the Utilization of Existing Spectrum – Higher Efficiency and Small Cells

Thanks to the industry’s relentless efforts, wireless technologies have been continuously evolving, offering ever higher efficiencies for the existing spectrum. Continuing on this path is the most obvious first step toward the 1000x goal. This means evolving HSPA+ to HSPA+ Advanced, LTE to LTE Advanced (including in unlicensed bands), Rev. A/B to DO Advanced, 1X to 1x Advanced, WCDMA to WCDMA+, Wi-Fi to 802.11ac etc. These upgrades significantly improve capacity, data rates and user experience.

Small cells are essential to increase the utilization of existing spectrum since they enable much greater reuse of the same spectrum also used by the macro network. Thanks to the advanced interference management and SON (Self Optimizing Network) techniques, the overall capacity increase enabled by small cells grows as the densification of the small cell deployment increases.

ASA: An Innovative Approach to Access Underutilized Spectrum

Although traditional licensing is the main solution, it may not be feasible in some cases. Some spectrum holders such as government users, because of the nature of their operations, may not be using the entire allocated spectrum in every part of their geographic boundaries on a 24x7 basis. For example spectrum for military radar may have been allocated on countrywide basis, but the radar operations may only be utilizing it at certain places such as coastline. In such cases, Authorized Shared Access(ASA) is an ideal approach for 3G/4G operators to access the underutilized spectrum in a mutually beneficial way. It proposes a new regulatory framework to share the spectrum in terms of time or location on an exclusive basis, without interfering with the incumbent’s operations.

Everybody wins with ASA—Incumbent spectrum holders can monetize their underutilized spectrum, 3G/4G operators can cost-effectively get new spectrum for exclusive use, ensuring reliability, and predictability for long time investments; regulators can pragmatically address the ever increasing request for new spectrum for mobile broadband in a timely manner.

ASA Targets Harmonized Spectrum

ASA can potentially unlock 100s of MHz of high-quality spectrum for 3G/4G, especially in higher spectrum bands. Along with our partners, we are already working on identifying globally harmonized bands for ASA. The initial focus is to target bands for which commercial devices are either already available in the market or will soon be available. The advantage of using harmonized bands with commercial device support is that operators can quickly start using the ASA spectrum, and leverage large economies of scale. Moreover, ASA doesn’t need any standards change, making it simple to deploy, and hence even more attractive.

ASA is also well suited for small cells because of their lower transmit power, which allows them to be deployed geographically much closer to an incumbent's operations. Of course, deployments of macro cells are also enabled by ASA.

Making the best use of unlicensed spectrum

For operators solving the 1000x challenge, licensed spectrum is the foundation. Equally important is leveraging all of the available spectrum, including unlicensed. The best way to make use of unlicensed spectrum is to aggregate it with a licensed LTE anchor.

There are two solutions for aggregation: LTE – Wi-Fi link aggregation, for existing and new carrier Wi-Fi utilizing both 2.4 GHz and 5 GHz; and LTE in unlicensed (LTE-U) for new small cells utilizing 5GHz. Many operators will do both.

Spectrum Aggregation – Across Bands, Technologies and Types

Mobile wireless has spanned across many technologies (3G/4G/Wi-Fi), across several bands, and across different licensing models (licensed, unlicensed, very soon ASA). Aggregating all the available spectrum resources enables operators to increase overall network capacity and to provide best possible mobile broadband experience to users. With all the different spectrum variables, numerous aggregation scenarios are possible, wireless industry has developed and standardized many of those and continues to work on many more.

Carrier aggregations defined in EV-DO, HSPA+, LTE allows combining different bands of the same technology, as well as across licensed and unlicensed spectrum (for LTE Advanced).Supplemental Downlink (SDL) is a special case of carrier aggregation enabled by HSPA+ and LTE Advanced. It aggregates unpaired spectrum with the downlink of paired spectrum substantially increasing downlink capacity. SDL is on track to be commercially deployed globally (e.g. L-band/1400 MHz in Europe & 700MHz band in the US).